Large Volume Inorganic Chemicals - Ammonia ... - ammk-rks.net

Chapter 77.4.4 Particle formation (3): prill towerDescriptionEvaporated NP liquor from neutralisation is mixed with the required salts and recycled product.The final water content is approximately 0.5 %. The mixer overflows into a rotating prill bucketfrom which the slurry is sprayed into the prill tower. Fans at the bottom of the tower causeambient air to flow countercurrently to the droplets formed by solidification. The solid prills fallonto a rotating tower bottom and are scraped off and forwarded to the dry handling system. Theproduct leaving the prilling tower is screened to meet product specifications. Over and undersizematerial is returned to the process and the NPK product is sent to the conditioning section.Achieved environmental benefitsTable 7.8 shows the emission levels from prill towers in the production of NPK and CN.Emissionmg/m 3 kg/hour m 3 /hourDust 5 2.5NH 3 10 – 15 5 – 7.5500000NPK production via the nitrophosphate route, levelswithout abatement system (the dust emission dependson the AN content, the NH 3 emission is related to pH,temperature and the NH 3 /P 2 O 5 ratio of the NP acid)CN dust 20 7.4 370000 CN production, levels relate to a 40 tonnes/hour plantTable 7.8: Emission levels from prill towers in the production of NPK and CN[76, EFMA, 2000]Cross-media effectsNone believed likely.Operational dataNo specific information provided.ApplicabilityGenerally applicable. Nowadays in Western Europe, only one NPK prilling tower is inoperation. For NPK prilling, if not carried out in a favourable climatic environment, highinvestment costs can be expected.EconomicsNo information provided.302 Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilisers